我有两个表,"child"one_answers"parent","child"必须继承"parent的所有列,我在概念模型(类图)中使用两个表之间的"泛化"链接,当我生成物理模型时,它会给我这个结果:
create table child (
id INT4 null,
);
create table parent (
id INT4 null,
name INT4 null
);
alter table child
add constraint FK_CHILD_GENERALIZ_PARENT foreign key (id)
references parent(id)
on delete restrict on update restrict;
但在Postgresql中,继承不是FK约束,它必须给我:
create table child (
); INHERITS (parent);
我想念什么??
从概念模型生成Postgresql物理模型时,实际上似乎没有保留继承信息。
作为一个练习(你可能会说,为了的乐趣),我设计了一个粗略的解决方案。。。
- 拥有Postgres DBMS的可编辑版本(使用标准版本,或创建副本,或将其嵌入物理模型)
- 在此DBMS中,在Profile>Table下添加一个转换"PreserveInherits"(请参见下文)
- 在DBMS中,添加一个转换配置文件"PreserveHeritage",模型类型为"概念数据模型",并在后生成中使用上述"PreserveNherits"转换添加一个步骤
- 在CDM中使用Tools(工具)>Generate Physical Data Model(生成物理数据模型)时,确保在PDM Generation Options(PDM生成选项)的"Detail"(详细信息)选项卡中推送/选中"Enable transforms"(启用转换)
- 该技巧通过覆盖表上的Physical Options来生成所需的"inherits(foo)"选项
PreserveInherits转换的来源:
dim targetmap
dim targetmapcreation
sub DescentTargets(pkg, trfm)
dim obj
for each obj in pkg.tables
if not (obj.IsShortcut) then
dim src : set src = trfm.GetSource(obj)
if not (src is nothing) then targetmap.add src,obj
end if
next
for each obj in pkg.Packages
DescentTargets obj,trfm
next
end sub
function GetTargetObject(obj, model, trfm)
' global dims are not reset betweeen generations, use a timer to reset it sometimes
if isempty(targetmap) or datediff("s",targetmapcreation,time)>60 then
set targetmap = CreateObject("Scripting.Dictionary")
targetmapcreation = time
' fill map with information about target objects
DescentTargets model,trfm
end if
if targetmap.Exists(obj) then set GetTargetObject = targetmap.Item(obj)
end function
Sub %Transformation%(table, trfm)
' find origin entity
dim source : set source = trfm.GetSource(table)
if not (source is nothing) and source.IsShortcut then set source = source.TargetObject
if not (source is nothing) and source.ClassKind = cls_Entity then
' walk up to parent entity
dim link
for each link in source.InheritsFrom
dim cdmparent : set cdmparent = link.ParentEntity
if not (cdmparent is nothing) and cdmparent.IsShortcut then cdmparent = cdmparent.TargetObject
if not (cdmparent is nothing) then
' walk "back" to target table of parent entity
' trfm.GetParent(cdmparent) does not work as I hoped, use a helper function
dim pdmparent : set pdmparent = GetTargetObject(cdmparent,table.model,trfm)
if not (pdmparent is nothing) then
' msgbox "found parent table " & pdmparent.name
table.physicaloptions = "inherits (" & pdmparent.code & ")"
end if
end if
' TODO modify the code to deal with several inheritances...
exit for
next
end if
End Sub